Emery-wheel



G. HART! Emery -Whee1.

No. 226,066 Patented Mar. 30, 1880.

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GILBERT HART, OF DETROIT, MICHIGAN.

EMERY-WHEEL.

SPECIFICATION forming part of Letters Patent No. 226,066, dated March30, 1880.

' Application filed March 5, 1880. (Model) To all whom it may concern Beit known that I, GILBERT HART, a citij zen of the United States,residing at Detroit, in the county of WVayne and State of Michigan, haveinvented new and useful Improve- I ments in Emery-YVheels, of which thefollowing is a specification.

This invention relates to that class of grinding and polishing wheelswhich are molded from plastic compositions, its object being to provideagainst the well-known tendency of such wheels to burst or break bothlaterally and circumierentially from centrifugal strain I when rotatedat the high speed required for their efficient action. I

It has been customary to brace and strength on this class of grindingand polishing wheels by embedding within the composition at the time ofmoldingametal plate or disk arranged concentrically with the wheel, ortwo such parallel disks, one or more disks of wire-cloth, or plates ofperforated sheet metal but in all of thesemodcs of bracing there areleft portions of the composition extending from centerv to periphery ofa wheel on each side of and between the braces which arenotstrengthened, and owing to which the wheel has still a tendency to splitlaterally, and there is liability of the peripheral portions of theseembraced layers to fly oft circumferentially.

Wheels have also been formed from compositions having mixed therewithhard abrading substances, such as pulverized glass, fine granulatediron, fine iron or steel filings and borings, and steel wires arrangedradially; but in these wheels the said hard abrading substances form theeffective working surfaces of the wheel, and are simply held in positionby the plastic portion of the composition.

My present invention differs from all those mentioned in providing agrinding and polishing wheel in which the abrading and polish sition ofemery, corundum, or similar material, thoroughly braced by means ofembedded fragments of metal, such as short pieces of wire mixed atrandom, as far as relative position is concerned, but about evenly as toquantity in the composition while in its plastic condition beforemolding, the wire or metal fragments being of such nature as to l wearaway evenly with or more easily than the composition. There are thusleft no unbraccd diametric layers of the composition, rendering thewheel weaker in any direction than in others.

In the accompanying drawings, Figure I is a side view of a compositiongrinding and polishing wheel constructed according to myin vention. Fig.II is a diametrio section of the same. Fig. III is a view of amodification of the wheel.

The letter A designates the main body of the wheel, which may be formedof any of the ordinary abrading and polishing compositions containingemery, corundum, or similar material, and 1) indicates short pieces ofwire, preferably copper wire, though fragments of other metals may beused provided they are of such nature as to wear away evenly with ormore easily than the composition. These shortpieces of wire or fragmentsof metal, it will be observed, are thoroughly mixed in the compositionwithout regard to regularity of position or direction, and thus form abinding and bracing medium, givinga practically uniform strength to theentire mass in which it is located as regards both circumferential andlateral strain.

The fragments of wire or other forms of metal are to be introduced andmixed with the composition before the mass is placed in the mold, whichmay be of the usual construction for molding composition wheels, and thesubsequent dressing and curing of the wheel should be in accordance withthe usual methods.

Owing to the nature of the wire or metal fragments to wear away readilywhen the wheel is used, they do not at all interfere with the abrasiveand polishing action of the composition, While forming effectivebracing.

In molding a wheel according to the modification shown in Fig. III,Ifirstplace upon the bottom of the mold a thin layer, 0, of thecomposition without admixture of the metal fragments. Upon this is thenlaid a thicker central layer, 0, of the composition having the metalfragments mixed therewith, and upon this central layeris then placedanother outside layer, 0, of the plain composition. When the centrallayer is laid it should be pressed upon the first-laid layer of plaincomposition, so that a portion of its metal fragments will partiallypenetrate the said plain layer but not pass through the same, and whenthe last layer of plain composition is laid it should be pressed uponthe central layer for the same purpose. The adjacent surfaces of theseverallayers soon agglomerate and becomehomogeneous, so that whencompleted the wheel has plain composition side faces suitable forlight-pressure polishing, the wheel being practically as thoroughlybraced as though the metal fragments appeared on the side faces.

What I claim is- A grinding and polishing wheel in which the abradin gand polishing substance is composed of a plastic composition of emery,corundum, or similar material braced by means of embedded fragments ofmetal mixed irregularly or at random therein, and of such nature as towear away by friction as readily or more readily than the composition ofwhich the main body of the wheel is formed, substantially as described.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

GILBERT HART.

Witnesses:

JAMES L. Nonnrs, J AMES A. RUTHERFORD.

